On Heating by Hot Water. 



305 



It is a great desideratum with gardeners, as far at least as my 

 experience goes, to get up heat in a short time, and their ordinary 

 test of the excellence of a hot water apparatus is, how speedily 

 they can get the water to boil. Where an apparatus is properly 

 constructed this can seldom be effected without a most extravagant 

 waste of fuel. The water in a hot water apparatus, constructed 

 on the most perfect principles, will take as many hours to heat 

 to the boiling point as the pipes winch contain it are inches in 

 diameter, and it will also cool in the same ratio. Four inch pipes 

 will accordingly take four hours to reach the temperature of 200°, 

 and they can be heated to the boiling point in one hour, only by 

 the consumption of four times as much fuel as would suffice if 

 properly applied, or in fact, allowing for the waste of heat by the 

 chimney, which increases under such circumstances very rapidly, 

 five or six times as much fuel as is really necessary will be con- 

 sumed by a gardener zealous of the honour of his apparatus. It is 

 of course possible, by having a furnace and boiler excessively large 

 in comparison with the pipes, to construct an apparatus with four 

 inch pipes which shall boil in an hour ; but the necessary con- 

 sequence will be that such a furnace would burn during every hour 

 of the night four times as much fuel as can possibly be effective in 

 heating the building to which it is applied. 



If a house is to be heated rapidly, the pipes should be of the 

 smallest diameter which is consistent with a free circulation, but it 

 must be borne in mind that such pipes will also cool with equal 

 rapidity ; and, if the heat is to be maintained through the night, 

 the furnace must be so constructed as to contain a large quantity 

 of fuel, but only to allow of a very slow consumption, much after 

 the manner of Dr. Arnott's Stove. Now such a furnace, though 

 theoretically very easy, and practically not very difficult of con- 

 struction, requires an almost scientific nicety of management not to 

 be expected from common gardeners. There are moreover several 

 objections to small pipes, one of the most material of which is this, 

 vol ii. 2nd. series. 3 B 



